1. Field of the Invention
The present invention is in the field of position tracking and machine control systems, and, more specifically, is directed to the field of using position and angular rate sensors for machine control systems.
2. Discussion of the Prior Art
Rate gyros are well known in the vehicle arts for determining heading and yaw of a vehicle like a car. They are an integral part of improving steering and handling in cars.
More specifically, gyros are commonly used to provide an estimate of a rate of rotation about a particular axis. In wheeled vehicle applications, a gyro can be used to help guide and navigate a wheeled vehicle. In other wheeled vehicle applications, a single-axis gyro is typically used to feed an estimate of yaw rate to a stability control system that is capable of making adjustments to vehicle operation that help increase vehicle stability under a wide variety of operating conditions.
Vehicle stability control systems commonly include a computer that executes an algorithm that monitors vehicle operation. Usually, several sensors and engine operation is monitored. If the algorithm determines that the vehicle is unstable or is in danger of becoming unstable, vehicle operation is adjusted in a manner intended to increase stability. Usually, vehicle operation is adjusted by applying one or more brakes. Engine speed can also be controlled.
Sensors that are typically monitored include one or more wheel speed sensors, a steering angle sensor, a yaw rate sensor, and a lateral acceleration sensor. During vehicle operation, signals from one or more of these sensors are used to determine an acceptable yaw rate threshold given the speed of the vehicle, its lateral acceleration, and its steer angle. If the actual yaw rate provided from the yaw rate sensor exceeds the acceptable yaw rate threshold, vehicle stability control is initiated.
However, the prior art rate gyros were not used for precise estimation of relative angular coordinates between at least two parts of a vehicle, including a main body and at least one ground controllable wheel.